Percussive tool



y 1942- w. A. SMITH, SR I 2,283,292

PERCUSS IVE TOOL Filed March 20, 1941 mvEN'rdR IIZi'ZliamZI-Skzif/v 5v HIS ATTORNEY.

Patented May 19, 1942 lTE I g am 2,283,292 PERCUSSIVE TOOL William A. .Smith, sr ethens, Pa., assignorto Ingersoll-Rand Company, New York, N. Y., a corporation of New Jersey Application March 20, 1941, Serial No. 384,256 2 Claims. I r 01. 125-33) This invention relates to percussive tools, and' more particularly to a percussive tool driven mechanically through suitable devices and connections by an individual, power element;

One object of the invention is to construct a rugged and compact percussive tool that may be conveniently manipulated and guided with respect to the work and which will be capable of delivering forceful blows at a rapid rate of speed to the working implement intended to be actuated by the percussive tool.

Another object is to enable the power element the practice of the invention,

Figure 2 is a transverse view taken through Figure 1 on the line 22, 7 7

Figure 3 is a side view of a detail partly broken away, and

Figured is a transverse view taken through Figure 1 onthe line 44.

Referring more particularly to the drawing,

2B designates, in general, a percussive tool and 2i a working implement which the percussive tool is intended to actuate.

In the form of the invention illustrated, the percussive tool comprises a crank casing 22 having an end surface 23 serving as a seat for a' support member 24 which may be secured to the crank casing 22 in any suitable manner. The support member 24 is hollowto receive a rod 25 of a length to project from the ends of-the support member for the accommodation of hollow grip members 26 that may be grasped for manipulating the tool and guidin it with respect to'the work.

In the front end of the crankcasing is an enlarged recess 27 to receive the end of a cylinder 28, the opposite end of which is suitably attached to a front head 29 containing a bushing3ll for guiding the working implement 2!. Within the cylinder 28 is a percussive element designated in its entirety, by 3! and comprising a hollow plunger 32 which is sealed at its rearward end by a plug 33 press-fitted thereinto and has a hollow extension 34 of reduced diameter at-its front end. The plunger 32 has a nice sliding fit in the cylinder 28, and in the interior or chamber 35 of the plunger is a reciprocatory piston 36 ;having a reduced stem 31 extending slidably though the hollowextension 34 to strike the working implement 2i.

As a preferred arrangement, the plunger32 is against provided with an annular groove 38 in its pe-' riphery and in the wall of the plunger, at points located suitable distances from the, rear: and

frontends of the chamber 35, are ports 39 and Ail, respectively, to afford communication between the annular groove 38 and the interior of the plunger. The portionsof the chamber 35 lying rearwardly of thelports 39 and forwardly of the ports fill constitute cushioning chambers 4i and 32, respectively, wherein atmospheric air will be entrapped to form a cushion between the piston 3t and the end surfaces of the. chamber 35.

The plug33 is recessed to receive the end of a connecting rod 43v and a wrist pin 44 extending through the connecting rod is press-fitted into the plug 33 and the plunger 32 to lock the plug securely to the plunger. The connecting rod 43 lies in the chamber 45 in the crank casing 22 and is connected at its other end to a crank pin 46 on the web 41 of a crank shaft '48 extending through a side wall 29 of the crank casing 22.

The connecting rod. may be retained onthe crank pin as in any suitable manner, as for example by a washer 50 held in position by a nut 51 threaded on the end of the crank pin. An antifriction bearing 52 in the wall 49 supports the shaft 43 adjacent the web 41, and the shaft extends through a gear chamber 53 on the side of the crank casing and is supported by a cover 54- 'forming a closure for the gear chamber 53 and secured to the casing 22 by bolts 55.

.The portion of'theshaft 48 lying outside of cover 54 by an inner surface 58 on the cover 54 lying directly in front of the gear.

The gear 56 is shown as being of the spur type and its teeth mesh with a driving pinion 59 hav ing trunnions Ell and BI that extend, respectively, into the wall 49 and the cover 54 and are respondingly shaped end'65 of a flexible cable 18 slidable in the cover 54.

66 having its other end connected to a prime mover (not shown) as for example an internal combustion engine or an electrical motor. A conduit 61 enclosing the cable 66 is threadedly connected to a bushing 68 in the cover 54 and abutting the trunnion 6|.

Suitable means are provided for holding the "88 is provided in its periphery with a second gear 56 fixedly with respect to the shaft 48 when- In the form of the invention illustrated, force I is applied to the clutch member II for actuating it by a lever 74 overlying the grip member 26 and being pivotally connected to a pin 15 in the support member 24. The pin 15 lies beneath the rod and on the adjacent portion of the lever is a wing 18 to seat upon the head I! of a plunger A spring 19 is interposed between the head 11 of the plunger and the cover to normally hold the plunger "in retracted position and thus to hold the lever 14 in k readiness for depressing the plunger.

The opposite or lower end 88 of the plunger extends into the bore 8! of the cover 54 to engage a radial shoulder 82 in the periphery of a thrust member 83 seated in the bore 3|. member 83 is rotatable in the bore 8| and its interior surface serves as a bearing for the outer end of the shaft 38, or, more particularly, for rollers 84 arranged about the end of the shaft.

The thrust member 83 is provided on its periphery with a flange 85 to seat against a shoulder 86 in the bore Sl'for preventing movement of the thrust member in an outwardly direction, and on the inner surface of the thrust member are a plurality of grooves 8'? to accommodate balls 88 serving to translate the rotary movement of the thrust'member into longitudinal movement of the clutch member 1 I. The grooves 81 are'all described on the same circle and of gradually decreasing depthfrom an end 89 which is suitably shaped to conform to the curvature of a, ball 88.

Interposed between the thrust member 83 and the clutch member If is a plate 96 which is slidable freely in the bore 8 l' and held against rotary movement by diametrically opposed lugs 9| on its periphery extending into grooves 92 inthe bore 8!. In the side of the plate 98 confronting the inner end of the thrust member 83 are grooves 93 of the same conformation as the The thrust H grooves 81, although reversed so that their shallow ends point in the same direction as the deep ends 89 of the grooves 81.

The plate 98 is so positioned with respect to the thrust member 83 that the balls 88 will lie in both the grooves 81 .and the grooves 93, and on radial shoulder designated 95 and preferably positioned diametrically opposite the shoulder 82. .The shoulder 95 serves as a seat for a plunger 96 slidable in a bore 91 in the cover 54 and pressed against the shoulder 95 by a spring 98 interposed between the plunger and a plug 99 threaded into the outer end of the bore 91.

The operation of the device is as follows: Whenever it is intended to actuate the working implement 2|, and assuming of course that the gear 58 is being rotated, the lever 14 is rocked about the pivot for pressing the plunger 18 downwardly. This movement of the plunger causes the thrust member 83 to be rotated about the shaft and the balls 88 to be shifted toward the shallow ends of both the grooves 81 and 93.

In assuming the described position the balls 88 will shift the plate 98, the thrust bearing 94 and the clutch member H inwardly along the shaft 48 and force the clutch member into frictional engagement with the coniform surface 18; Inasmuch as the clutch member H is interlockingly engaged with the shaft 48 the shaft will then rotate with the gear and cause the plunger 32 to be reciprocated in the cylinder 28.

' During the downward movement of the plunger the piston 36 will be in its rearmost limiting position and when the plunger reaches the lowermost limit of its movement the piston is impelled forwardly to-strike against the Working implement 2|. On this stroke of the piston the air in the cushioning chamber 42 will be compressed after the piston covers the ports 40 but not to such an extent as to seriously diminish the force of the blow of the piston.

During the rearward stroke of the plunger the piston 38 will beretracted from the working im plement and will be impelled into the rearward end of the chamber 35 at the instant of reversal of the plunger. The piston will, however, be prevented from striking the plug 33 by the air entrapped in the cushioning chamber 45 and will remain in its rearmost limiting position relatively to the plunger during the forward movement of the latter. Upon .the subsequent reversal of the plunger the piston will continue in aforwardly direction and strike heavily against the working implement. This cycle of operation may be continued as long as theclutch member remainsin engagement with the surface 10.

Upon completion of the drilling operation, or

iffor another reasonit should be desired to discontinue the application of blows to the working implement, the pressure against the lever 14 is' will rotate the thrust member 83 to its initial position and the parts serving to transmit movement from the thrust member to the clutch member H for engaging the gear 58 may then adjust themselves to their original positions. In this way the frictional engagement between the clutch member and the coniform surface Ill will be broken and the percussive element will come to rest.

I claim:

1. A percussive tool, comprising a casing having a handle, a reciprocatory percussive element in the casing, a crank shaft in the casing, means 7 for transmitting movement from the crank shaft to the percussive element, a gear freely rotatable on the crank shaft, a pinion for drivingrthe gear,

2. A percussive tool, comprising a casing havl0 ing a handle, a reciprocatory percussive element in the casing, a crank shaft in the casing for actuating the percussive element, means for driving the crank shaft, a pair of clutch members for effecting a driving connection between the driving means and the crank shaft, thrust means for actuating one clutch member with respect to the other clutch member, and a bearing in the thrust means for the crank shaft.

WILLIAM A. SMITH, SR. 

